I work for a copper clad laminate manufacturer. One of our customer (PCB shop) has wicking problem for plated through hole. They said they found "laminate void in glass fabric " by microsection. (They mean the glass yarns are not wetted by epoxy resin, not void in resin after lamination. Usually wicking is related to rough drill or over desmear process). I made microsection by myself and make real good polish. After that I believe the so called "laminate void in glass fabric" is the result of poor polishing i.e. scratches. (My microsection can see a single yarn but their microsection can't). I attached some detail dimension for your reference: Glass yarns diameter: 1080 (5 microns), 7628 (9 microns) Extect abrasive paper P1200 grit: grit size 10 to 20 microns, average 15 microns Multipolish Al2O3: 0.05 microns Specification for laminate void is < 3 mil. (IPC-4101 & MIL-PRF-5510 F). Our product is 5 mil laminate so the "laminate void will be far less than 3 mil.) My customer show us a article dated at August 1982 by PC FAB, "Laminate Porosity Causes". But the pictures are too blur after copy many times. The authors are J.F. Nejedlik and A.M. DeSantis. My questions are as follows: 1. Anyone has the experience of "wicking" or "blow hole" due to the wetting problem of glass fabric? 2. Is microsection technic with 100 X to 200 X magnification capable of tell the wetting condition of single yarn of glass fabric? Any inputs will be greatly appreciated!!! William Wang ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################